Oreocharis tetrapterus F.Wen, B.Pan & T.V.Do, 2019

Pan, Bo, Tang, Guang-Da, Do, Truong Van, Maciejewski, Stephen, Deng, Chong-Lang & Wen, Fang, 2019, Oreocharis tetrapterus (Gesneriaceae), a new species from East Guangxi, China, PhytoKeys 131, pp. 83-89 : 83

Oreocharis tetrapterus F.Wen, B.Pan & T.V.Do sp. nov. Figures 1 , 2 , 3 , 4A

Diagnosis.

The large bright yellow corolla is 2 lobed with the adaxial and abaxial lips both consistently 2-lobed, with irregular dark reddish-brown spots on the interior surfaces of the corolla lobes and 2 fertile stamens in posterior position distinguishes Oreocharis tetrapterus from all other species of Oreocharis s. l.

Type.

China. Guangxi: Hezhou City, Lisong Town, Gupo Mountain, 24°39'N, 111°36'E, elev. ca. 950 m, on moist surface of granite rocks, in flowering, 25 August 2018, Wen Fang WF160825-01 (holotype: IBK!, isotype: IBK!).

Description.

Perennial herb, rhizome stem inconspicuous, 4-10 mm long, 3-4 mm in diam. Leaves 8-14, in basal rosette; petiole cylindric, 1-5 cm long, 2-3 mm in diam., sparsely to densely curly brown pubescent; leaf blade green to dark green, ovate to broadly elliptic, 3.0-5.5 × 2.2-3.5 cm, adaxially pubescent with nearly erect white hairs, abaxially sparsely pubescent to nearly glabrous but with dense white, slightly curly pubescence along main and lateral veins, lateral veins 5-6 on each side of midrib, adaxially inconspicuously sunk, adaxially conspicuously raised, apex obtuse to rounded, base often slightly asymmetric, margin crenate with 15-20 teeth on each side, more obvious on the lower half. Cymes axillary, inflorescence (1-)2-4-flowered; peduncle greenish brown to brown, 4-8 cm long, ca. 1.5 mm in diam., densely white pubescent; bracts 2, opposite, lanceolate to linear, ca. 5.0 × 1.0-1.5 mm, adaxially appressed white pubescent, abaxially nearly glabrous, margin nearly entire; pedicel green, 7-12 mm long, ca. 1 mm in diam., pubescent with dense, nearly erect hairs. Calyx green, 4-lobed to the base, lobes nearly equal, linear, 6-8 mm long, ca. 1.2 mm wide at base, outside white pubescent, inside glabrous. Corolla 2.2-2.8 cm long, bright yellow, inner side of corolla lobes with irregular dark reddish-brown spots, sometimes entire upper lobes reddish-brown, outside densely white glandular- and eglandular-pubescent, inside glandular puberulent in the throat and on adaxial lobes, tube broadly infundibuliform, 1.8-2.5 cm long, 6.5-8.5 mm in diam.; limb 2-lipped; adaxial lip 2-lobed divided to more than halfway, lobes broadly oblong to semiorbicular, 5-7 × 7-8 mm, abaxial lip 2-lobed to base, oblong, 8-10 × 5.5-7 mm. Stamens 2, in posterior position, 1.5-1.8 cm long, adnate to corolla 6-8 mm from base; filaments linear, yellow, glabrous; anthers narrowly horseshoe-shaped, apex acute, 2-loculed, dehiscing longitudinally; staminode 1, ca. 1.5 mm long, inserted at tube base. Disc tubular, ca. 5 mm high, yellowish green, margin undulate. Pistil 2.5-3 cm long when all corolla lobes outspread and flower completely opened; ovary green, cylindrical, glabrous, 1.8-2 cm long; style pale green, glabrous, 6-10 mm long; stigma bilobed, flabellate, pale green. Capsule linear, dehiscent but commonly one side of the capsule dehiscent first, loculicidal, straight in relation to pedicel, 3.5-4.5 cm long.

Phenology.

Flowering in August; fruiting in October.

Etymology.

The specific epithet, ' tetrapterus ' from the Greek meaning having four wings or wing-like appendages. Here it refers to the four ‘wing-like’ lobes of the corolla, with adaxial and abaxial lips both having 2 lobes.,

Vernacular name.

The Chinese name of this new species is 姑婆山马铃苣苔. The pronunciation of the Chinese of this species is 'Gū Pó Shān Mǎ Líng Jù Tái’.

Distribution and ecology.

Oreocharis tetrapterus is currently known only from one population of ca. 50 individuals at the type locality. The species may be endangered, but more data is needed to evaluate this reliably. The species grows on moist surfaces, on moss-covered granite rocks with other plants under subtropical bamboo and evergreen broad-leaved forest cover in Hezhou City, Guangxi.

Notes.

We understand most other Gesneriaceae with two stamens have them in the anterior position, but this special character, two stamens in the posterior position, has also evolved outside the Oerocharis s. l. in the South American Sarmienta Ruiz & Pavon ( Ruiz and Pavon 1794) and the Asian/African Epithema Blume ( Blume 1826, Bransgrove and Middleton 2015). Oreocharis tetrapterus is morphologically unique within Oreocharis s. l. and can be easily distinguished from the other species with four lobes by its zygomorphic corolla, whereas the others are actinomorphic, for example O. sinensis and O. esquirolii ( O. esquirolii also has 5-lobed corolla type, occasionally) ( Fig. 4 ).

Figures

Figure 1. Oreocharis tetrapterus F. Wen, B. Pan & T. V. Do sp. nov. A habit B lateral view of flower C adaxial surfaces of calyx lobes D opened corolla for showing the two fertile stamens in posterior position E pistil with disc, sepals removed F stigma G anthers in side view. Drawn by Wen-Hong Lin from the holotype.

Figure 2. Oreocharis tetrapterus F. Wen, B. Pan & T. V. Do sp. nov. in its natural habitat A habitat B flowering plant C plant with flowering cymes D frontal view of corolla E lateral view of corolla F top view of corolla. Photographed by Bo Pan and Fang Wen, charted by Wen-Hua Xu.

Figure 3. Oreocharis tetrapterus F. Wen, B. Pan & T. V. Do sp. nov. A lateral view of flower B top view of flower C lateral view of corolla and pistil and calyx lobes D adaxial surface of calyx lobes E abaxial surface of calyx lobes F pistil, sepals removed G opened corolla for showing stamens in posterior position H anthers, abaxial view? I adaxial leaf surface J abaxial leaf surface K peduncle indumentum. Photographed by Fang Wen and Bo Pan in the field, charted by Wen-Hua Xu.

Figure 4. Some species in Oreocharis with typically four corolla lobes A Oreocharis tetrapterus F. Wen, B. Pan & T. V. Do sp. nov. B O. sinensis (Oliv.) Mich. Moeller & A. Weber (1 Lateral view of flowering cyme 2 Frontal view of flowering cyme) D O. esquirolii Leveille (1 Corolla with four lobes and four stamens 2 Corolla with five lobes and five stamens). Photographed by Fang Wen and Bo Pan, charted by Wen-Hua Xu.